1. Field of the Invention
This invention relates to laundry concentrates adapted to be diluted with water by the consumer prior to use.
2. Description of Related Art
There is a trend in the household products and personal care industries to provide products in concentrated form which are adapted to be diluted with water by the consumer prior to use. This approach reduces the bulk of packaging which needs to be disposed of by the consumer and reduces the shipping and handling costs associated with distribution of such products.
Laundry concentrates such as fabric softeners, fabric and dishwasher detergents may be provided with a high content of active ingredients such that, when diluted by the consumer per packaging instructions, the diluted product will contain an amount of active ingredients normally present in a non-concentrated product.
However, the provision of concentrated liquids gives rise to a number of problems, including viscosity control and stability.
Concentrated liquids tend to exhibit a higher viscosity due to the high content of surfactants, builders, electrolytes, fabric softeners and/or other components present in the concentrate. Concentrates having viscosities in excess of 1500 cps (mpas) tend to be difficult to pour from the packaging container, while pourable, lower viscosity concentrates tend to have insufficient viscosity when appropriately diluted by the consumer thereby reducing consumer appeal.
One approach to dealing with poor post dilution viscosity is to include in the liquid concentrate formulation one or more organic or inorganic thickening agents such as swelling clays, alumina, gums, polymeric materials or cellulosic polymers. However, the use of such thickening additives tends to worsen the problem of concentrate pourability and imparts only a minimal viscosity increase to the diluted concentrate.
Hydrophilic polymeric materials have also been used in liquid detergent concentrates as viscosity control agents. For example, U.S. Pat. No. 4,715,969 discloses that the addition of less than about 0.5% by weight of a polyacrylate polymer, e.g., sodium polyacrylate, having a molecular weight from about 1,000 to 5,000, to aqueous detergent compositions containing primarily anionic surfactants will stabilize the viscosity of the composition and prevent a major increase in viscosity after a period of storage of the formulated composition. Also, EP 301,883 discloses similar compositions containing from about 0.1 to 20% by weight of a viscosity reducing, water soluble polymer such as polyethylene glycol, dextran or a dextran sulfonate.
Concentrated fabric softener compositions are also known in the prior art. For example, GB 2007734 discloses a fabric softener concentrate comprising a mixture of non-ionic ethoxy fatty alcohol surfactant, a water insoluble oil and a quaternary ammonium salt such as dimethyl distearyl ammonium chloride. The concentrate is adapted to be dispersed into water to provide a diluted fabric softener dispersion. In addition, EPA 0503221 A1 discloses concentrated fabric softener compositions which are said to retain viscosity after dilution with water. The concentrate comprises an aqueous dispersion of a mixture of a fatty alcohol ethoxylate, a nonionic hydrophilic polymer, a cationic fabric softener, a highly branched fatty alcohol of 8 to 18 carbon atoms and a linear or cyclic polydialkylsiloxane.
While these and other approaches tend to enhance concentrate pourability, they do not solve the problem of low post-dilution viscosity or stability of the diluted concentrate.
Accordingly, it is an object of the invention to provide a liquid laundry concentrate which exhibits a sufficiently low viscosity such that it is readily pourable from its packaging container and which also exhibits a viscosity after appropriate dilution with water which is at least 50 cps, thereby contributing to consumer appeal.